A conventional mail sorter includes a synchronous transfer section, which charges mail into a conveyor box while mail holder sections are shifted in synchronization with the movement of the conveyor boxes for sorting the mail, so that the mail holder sections are adapted to transfer the mail to the conveyor boxes while a fixed section is moving in synchronization with the movement of the conveyor boxes.
Such a conventional mail sorter must transfer mail timely to a moving conveyor box through a mail holder section. However, the time interval when a receipt port of the conveyor box registers with the mail holder is an instant, and, after that, the facing state of both the receipt port of the conveyor box and the mail holder section is gradually changed to a V-shaped, bent arrangement state and the conveyor box and mail holder are separated from each other. Thus, transferable time therebetween is short, and when the transfer timing is shifted even a little, transfer failure can be often generated.
Thus, to be able to reliably transfer mail supplied from the mail charging line timely to a conveyor basket on the mail sorting line by extending the transferable time for mail the present inventors developed a mail sorting and distributing transfer system 200 in which after mail supplied from the mail charging line as shown in FIG. 6 was received in a transfer basket 220 hung at an outer circumferential edge of a mail sorting and distributing turn table 210, the mail is transferred to a predetermined conveyor basket 230, which circulates on a mail sorting line through an openable transfer port 222 provided on the bottom of the transfer basket 220.
However, since the mail sorting and distributing transfer system 200, which is a related art of the present invention as shown in FIG. 6, is circulated on a traveling rail 242b on only the inner circumferential side of the mail sorting line by hanging the transfer basket 230 by one side, a rotational moment F is generated by the conveyor basket 230 itself, and the self weight of mail while using a traveling roller 231c provided on a traveling rail 242b of the conveyor basket 230 and a guide roller 231b provided on the guide rail side as a base point, and excess conveying power is required by traveling resistance due to this rotational moment F. Accordingly, there were problems that upsizing of a driving source is not avoided and errors in transferring the mail from the transfer basket 220 to the conveyor basket 230 can be generated.
The mail sorting line has a horizontal bend and a vertical bend connected by a transfer zone. Further, connecting portions which, connect adjacent conveyor baskets to each other have a rotating shaft, and a rotating shaft of the traveling roller 231c and a rotating shaft of the guide roller 231b are separately arranged at non-intersection positions respectively, a torsion phenomenon is generated between the traveling roller 231c and the guide roller 231b in the transfer zone between a horizontal bend and a vertical bend forming a compound curve whose line is not in a plane, but is three-dimensional, and conveying trouble is caused by further traveling resistance due to this torsion phenomenon. Accordingly there was a problem that trouble can occur in a smooth sorting operation of mail M.